Predicting the current and future potential distributions and biotic interactions between an herbivorous insect and its host plants in southern Africa

Paulina P Fendinat, Israel Temitope Borokini 

Climate change will have profound impacts on species distributions and persistence in the near future, however, biotic interactions may mitigate climate effects among interacting species. In this study, we fitted species distribution models (SDMs) to predict the current and future habitat suitability of Gonimbrasia belina, a culturally and economically significant insect in southern Africa, and 11 of its host plants. SDMs were fitted with four algorithms using publicly accessible species occurrence records and bioclimatic variables (1970-2000) at 1 km resolution, while predicted habitat suitability were generated using weighted model ensembles. Future predictions were generated using four shared socioeconomic pathways of the EC-Earth3-Veg general circulation model (2061-2080). We also quantified ecological niche overlap (Schoener’s D) between the insect and the host plants with equivalency tests (1,000 randomizations) to evaluate statistical significance. Results show strong contributions and constraints of predictors representing water availability and water-energy balance to the distributions of the 12 species. G. belina and seven host plants were predicted to lose portions of their future suitable habitats, while the remaining four hosts may experience range expansions under climate change. Niche overlap was significantly lower between G. belina and most of its host plants (D=0.06–0.65) indicating a generalist herbivorous relationship. Range losses may disrupt biotic interactions between G. belina and some of its host plants, but herbivorous relationships may be sustained in predicted climatic refugia and with climate-adapted host plants. Nonetheless, long-term persistence of G. belina will depend on sustainable harvesting and protection of host plant diversity.